Odorizing mixture for an odorless gas fuel

Abstract

Composition which can be used in particular as odorant for a gaseous fuel, more particularly natural gas, comprising: from 0.1 to 49.9% of an alkyl sulphide (I) of formula: R 1 —S—R 2  in which R 1 and R 2 , which are identical or different, represent: an alkyl radical comprising from 1 to 4 carbon atoms; or R 1 and R 2 , taken with the sulphur atom to which they are attached, represent a saturated or unsaturated ring comprising from 3 to 5 carbon atoms which is optionally substituted by a C 1 -C 4 alkyl or C 1 -C 4 alkenyl radical; from 50 to 99.8% of an alkyl acrylate (II), the alkyl radical of which comprises from 1 to 12 carbon atoms, preferably from 1 to 8; from 0.001 to 0.1 part by weight of a compound (III) which inhibits the polymerization of the alkyl acrylate (II).

1. Composition which can be used in particular as odorant for a gaseous fuel, more particularly natural gas, consisting of:
 from 0.1 to 49.9% of an alkyl sulphide (I) of formula: 
 R 1 —S—R 2    
  in which R 1  and R 2 , which are identical or different, and are selected from:
 an alkyl radical comprising from 1 to 4 carbon atoms; or 
 a saturated or unsaturated ring with the sulphur atom to which they are attached, comprising from 3 to 5 carbon atoms which is optionally substituted by a C 1 -C 4  alkyl or C 1 -C 4  alkenyl radical; 
 
 from 50 to 99.8% of an alkyl acrylate (II), the alkyl radical of which comprises from 1 to 12 carbon atoms; 
 from 0.001 to 0.1% of a compound (III) which inhibits the polymerization of the alkyl acrylate (II), comprising a single, stable nitroxide radical of formula (IV): 
 
       
         
           
           
               
               
           
         
       
       in which R 3  and R 4  are selected from:
 a tertiary or secondary hydrocarbon radical comprising from 2 to 30 carbon atoms, and optionally one or more heteroatoms chosen from sulphur, phosphorus, nitrogen or oxygen; or 
 a cyclic hydrocarbon radical with the nitrogen atom to which they are attached, comprising from 4 to 10 carbon atoms, the said radical optionally being substituted. 
 
     
     
       2. Composition according to  claim 1 , characterized in that it consisted of from 5 to 14.95% of compound (I), from 85 to 94.95% of compound (II) and from 0.005 to 0.05% of compound (III). 
     
     
       3. Composition according to  claim 1 , characterized in that the alkyl sulphide (I) is selected from tetrahydrothiophene (THT), methyl ethyl sulphide (MES), dimethyl sulphide (DMS) or diethyl sulphide (DES). 
     
     
       4. Composition according to  claim 1 , characterized in that the acrylic acid ester (II) is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl or dodecyl acrylates. 
     
     
       5. Composition according to  claim 1 , characterized in that the acrylic acid ester (II) is methyl acrylate or ethyl acrylate. 
     
     
       6. Composition according to  claim 1 , characterized in that it comprises tetrahydrothiophene (I) and ethyl acrylate (II). 
     
     
       7. Composition according to  claim 1 , characterized in that the inhibitor of formula (IV) is a compound derived from tetramethylpiperidine oxide of formula (IVa): 
       
         
           
           
               
               
           
         
       
       in which R 5  is selected from a hydroxyl, amino, R 6 COO— or R 6 CON— group and where R 6  is a C 1 -C 4  alkyl radical. 
     
     
       8. Composition according to  claim 1 , characterized in that the compound of formula (III) is selected from N-(tert-butyl)-N-(1-[ethoxy(ethyl)phosphino]propyl) nitroxide, N-(tert-butyl)-N-(1-diethylphosphono-2,2-dimethylpropyl) nitroxide or N-(tert-butyl)-N-(2-methyl-1-phenylpropyl) nitroxide. 
     
     
       9. Composition according to  claim 1 , characterized in that said alkyl radical of said alkyl acrylate (II) comprises from 1 to 8 carbon atoms. 
     
     
       10. Composition according to  claim 1 , characterized in that said tertiary or secondary hydrocarbon radical comprises from 4 to 15 carbon atoms. 
     
     
       11. Composition according to  claim 1 , characterized in that said cyclic hydrocarbon radical comprises from 4 to 6 carbon atoms. 
     
     
       12. Process for the odorization of an odourless gaseous fuel comprising the addition of an effective amount of the composition as defined in  claim 1 . 
     
     
       13. Odorization process according to  claim 12 , characterized in that the gaseous fuel is natural gas.